1st mod gone wrong - Wrist Twisters
 
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post #1 of 16 Old 09-06-2007, 02:22 PM Thread Starter
(Quintus) Pilus Prior
 
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1st mod gone wrong

Well, not horribly at least.

Bought a K&N replacement. It doesn't fit. It's jsut a scosh bigger than the stock one and says >B040D6 on the filter end.

The box says HA-9002.

Wrong filter inna box ? Or do I have to go and carve out the inside of my airbox. (Not gonna do that)

Any others have this alamadingdong ?

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post #2 of 16 Old 09-06-2007, 02:30 PM
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I had the same issue with mine. It was a very tight fit but it did go in.

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post #3 of 16 Old 09-06-2007, 02:33 PM Thread Starter
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Did it scrape the wire mesh ? Bend it ? Crush the vanes ? I'm pretty sure I couldn't get my 50 bucks back if I hurt the filter. I wanna be sure, ya dig ?

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post #4 of 16 Old 09-06-2007, 02:35 PM
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Take it back get a factory one.Air flow isn't one of the 919's power issues.

Unless you just really want one,but don't expect any improvment from K&N on the 9er.

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post #5 of 16 Old 09-06-2007, 02:38 PM Thread Starter
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Are you serial ? THAT would make me change shops in a heartbeat.

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post #6 of 16 Old 09-06-2007, 02:46 PM
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i thought the same thing at first. Try again, its real snug and needs to go in at the correct pecise angle. Dont force it but be stern, itll fit.

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post #7 of 16 Old 09-06-2007, 02:49 PM
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Quote:
Originally Posted by Lemonhead View Post
Did it scrape the wire mesh ? Bend it ? Crush the vanes ? I'm pretty sure I couldn't get my 50 bucks back if I hurt the filter. I wanna be sure, ya dig ?
It just barely scraped the mesh , but caused no damage.

Quote:
Originally Posted by tvetree View Post
Take it back get a factory one.Air flow isn't one of the 919's power issues.

Unless you just really want one,but don't expect any improvment from K&N on the 9er.
tvetree,you are absolutely right about the K&N and normally I would just use a factory unit but my K&N was a gift from a friend so I put it in.
I honestly could not tell a difference in performance, but the tone of the intake noise when you're on it hard sounds sooooo cool!

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post #8 of 16 Old 09-06-2007, 02:53 PM
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For LemonHead
Borrowed/stole from 919.org which is linked to rc-51 for this

Testing of aftermarket airfilters on the RC51 has yielded poor results. Typically there are no real world benefits to aftermarket filters for the RC51 as small hp gains can be obtained on topend, but only with a severe trade off for mid-range hp. Truth be told every single Honda sportbike in the last 10 years has had losses in power at some point in the rev range or even throughout it from the addition of K&N , EMGO, BMC filters etc... The only real exception being the Airbox Plus kit developed for the 900RR from Factory Pro tuning which does increase hp throughout the rev range on the 900RR, but in my experience requires some pretty extensive jetting to get it right.


Interesting info #1: Flow testing on the stock filters performed by Brian Sheridan of Sheridan Racing Design proved to us that the OEM filters are more than capable of flowing more air than the engine can use


Interesting info #2: Dyno Testing on the BMC filters showed a definite decrease in topend horsepower with only a very slight gain in the mid-range. dyno charts from testing on 02/23/02

Note: when testing new high flow filters it is imperative to allow them to be broke-in properly by getting some miles on the bike at normal riding speeds. The oil applied from the factory can be initially too thick & can cause flow problems which can mis-lead dyno results in either direction. You may initially get good dyno results, but when the oil dissipates & the flow increases your dyno results may worsen or vice versa. Simply put with the extra oil in the filter you might get a good or bad initial dyno run, but after the oil is thinned out the dyno results may change (& usually do) just depends on the bikes flow characteristics

Additional common dyno testing discrepancies are discussed here dyno tuning basics



Back in the old days all the bikes benefited from slapping some individual pod filters on & adding some larger fuel jets... Things have changed greatly in the last decade whereas it's not uncommon for today’s custom jet kits to use smaller main jets with slimmer needles etc... to gain more horsepower & a more linear power delivery instead of just following the old cliché of bigger is better.

Since originally posting this page I have received hundreds of further inquiries about testing methods involving ram-air & how do I know the aftermarket filters don't work etc... Well there are more ways than just dyno testing to get results. Utilizing an Air/Fuel meter while riding in real world conditions will reveal alot of what your bike is actually doing, but even then not everything may be as it seems, sometimes a rich condition will be reported when the reason is that too much air inside the airbox is causing turbulence & stalling the airflow etc...

Some airfilters do work on certain bikes & some don't affect performance at all, but most aren't worth a damn for the overall performance advantage. The OEM filters are tuned to a specific resonance inside the airbox & once you go altering that you get various results. You might get better top end, but poor low end or vice-versa or you might get better performance with a bad stumble that lasts only for only a 200 rpm range or you may simply get a dip in power at some point. The combimation of results is almost infinite.

The main thing to remember is that on streetbikes you need drivability. If you were to put a graduated scale on your throttle housing & make a mark on your throttle grip you would find that you rarely exceed 10% throttle while riding around, yup no crap, 10%! Even when aggressively leaving stoplights & such you really don't open up the throttle all that much. So you need to have your bike as responsive as it can be at low throttle positions & in the mid-range of the bike where you ride the most. Way too much emphasis is put on peak hp when in fact you rarely ride around at redline with a wide open throttle... It's all about better mid-range performance & that is coincidently where the high flow filters usually hurt performance.

Honda's are definitely more applicable to this issue than the other manufacturers. It would appear that Honda spends more R&D time than any of the other manufacturers to insure that the intake system on their bikes is finely matched to the flow characteristics of the motor. The airbox is perfectly tuned to accept x amount of air thru the filters & deliver it to the carbs or throttle bodies in a metered volume & every thing works perfectly in sync in the state of tune they must be in to pass EPA Emissions testing. Typically an alteration of the filter leads to too much turbulent air entering the airbox & usually ends up either leaning out the motor or stalling the airflow altogether.

What would be more beneficial for creating more horsepower would be a larger airbox, which would make a larger amount of air "available" for the motor to use as opposed to a greater volume of air that the engine would be "forced" to use if you went with hi flow filters or filterless. What you don't want to end up doing is putting more air into the airbox than the engine can mix with the fuel. If that happens then you have screwed up your air/fuel ratio & you will lose power.

I'm not going to outright say that there is nothing to be gained from aftermarket filters, but I will say that most top-notch tuners will sway you a different direction especially if you are riding a streetbike as opposed to a racebike. Citing drivability issues as the number one concern.

Another point routinely thrown in my face is that the aftermarket filters are "re-usuable" Which simply put means that not only are you spending $80-$100 for a filter, but you also now have to purchase an additional cleaning kit so that you can wash, dry & oil your expensive filter, but in less time that it takes you to just wash the re-usable filter I can remove my old OEM filter, throw it away, install a new one & be off riding... If you are one of those people that are going to argue the cost savings of aftermarket vs OEM filters then you are into the wrong sport as nothing about a sportbike is cheap, not the cost of the bikes, insurance or maintenance period & you should be prepared to pay a few bucks every 4000-8000 miles for a filter.

In the end one thing is for certain if you are going to use aftermarket filters & get any appreciable gains from them it's going to require a Powercommader, alot of dyno time & probably some creative airbox mods too, maybe even to the point of fabricating custom bellmouths to get it dialed in correctly & you must also consider that in some cases there are no gains to be had & in many a loss of performance or drivability can Occur!

BTW because someone always brings up the fact that they use K&N filters in their car or truck & they do work under those conditions I must add that I too use K&N filters in my vehicles & they do show definite increases in power & throttle response, but cars are differerent from current bikes in that they have a closed loop Fi system that can compensate for the air flow variance whereas bikes use an open loop Fi system that cannot automatically compensate. Adding supporting evidence to my theories of airbox turbulence you will be interested to know that K&N has developed many different types of turbulence diffuser inserts for many different makes of cars & trucks that lessen intake turbulence when using their filters to increase performance. So far nobody has developed a way to even test for turbulence on motorcycle induction systems let alone cure it...

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post #9 of 16 Old 09-06-2007, 02:54 PM
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Those are the correct box and filter numbers for the 919.

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post #10 of 16 Old 09-06-2007, 03:21 PM Thread Starter
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Thanks guys.

Sonova.....

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post #11 of 16 Old 09-06-2007, 03:44 PM
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Sorry,I like the k&N just not for the 919.I've used them in other bikes and noticed a difference(seat of pants or in my head who knows)both older Hondas.A CB1000C and a 74ish 750K.Used it in the CRX I had also...

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post #12 of 16 Old 09-06-2007, 04:03 PM Thread Starter
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What the article said about closed loop vs. open loop f.i. systems made sense without me being a super-tech head. Guess I'll not trust them darn hot rodders ennymoor.

I'll try to return it tamale.

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post #13 of 16 Old 09-06-2007, 05:41 PM
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Quote:
Originally Posted by tvetree View Post
Sorry,I like the k&N just not for the 919.I've used them in other bikes and noticed a difference(seat of pants or in my head who knows)both older Hondas.A CB1000C and a 74ish 750K.Used it in the CRX I had also...
I would wager to say the 74' Honda CB750 did not run properly with the K & N's unless someone was a expert at carb. tuning. Grab a handful of throttle and the motor would bog really bad. You could change mains, change slow speed jets, raise/lower the needles, and open/close the fuel screws until the cows came home. None of these modifications would work. The trick was to reshape the needles in a lathe using fine emery paper. Or toss the stock carbs. in favor of a set of 29 mm Mukuni smoothbores.

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post #14 of 16 Old 09-06-2007, 06:34 PM
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This is an easy solution. The filter is a little bigger. What's happening is on the inside of the airbox at the very opening there is a little ridge from the plastic mold that was not trimmed away very well. The filter is snagging on it.

Just get a razor knife and trim it away making sure not to leave any shavings in the airbox. The filter will then just slide right in.

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post #15 of 16 Old 09-07-2007, 08:17 PM
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Quote:
Originally Posted by MisterMike View Post
I would wager to say the 74' Honda CB750 did not run properly with the K & N's unless someone was a expert at carb. tuning. Grab a handful of throttle and the motor would bog really bad. You could change mains, change slow speed jets, raise/lower the needles, and open/close the fuel screws until the cows came home. None of these modifications would work. The trick was to reshape the needles in a lathe using fine emery paper. Or toss the stock carbs. in favor of a set of 29 mm Mukuni smoothbores.
Most likly you right,It was one of my first and while it ran great.I really didn't know what great was.Things are almost always better than they really where as I look back.
I'm not really old but I'm getting there a little faster than I should.(Gotta fix that)

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post #16 of 16 Old 09-07-2007, 10:13 PM
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If you want to make the stock filter flow better take off the wire screen. It is restrictive. You can just snip the wire with tin snips or wire cutters. But, like mentioned above the air filter is not the bottleneck for a stock 919. The flapper not modded is a bottleneck though.

Motorusher formally known as DirtySanchez919.
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